Hi Masami, On Fri, 31 Oct 2014 14:51:29 -0400, Masami Hiramatsu wrote: > Hi, > > Here is a sereis of patches for enabling "event cache" feature > to perf probe. Brendan gives me this cool idea, thanks! :) > > In this series, I added following options/features; > - --output option > We can save the probe definition command for given probe-event > instead of setting up the local tracing/kprobe_events. > > - --no-inlines option > We can avoid searching the inline functions in debuginfo. Usually > useful with wildcards since the wildcards will hit a huge amount > of probe-points. > > - $params special probe argument > $params is expanded to function parameters only, no locally defined > variables. This is useful for function-call tracing. > > - wildcard support for function name > Wildcard support is the key feature for this idea. Now we can use > '*foo*' for function name to define the probe-point. > > So by using all of them, we can make an "event cache" file on all > functions (except for inlined functions) as below. > > # perf probe --max-probes=100000 --no-inlines -a '* $params' -o event.cache > > builds "event.cache" file in which event settings for > all function entries, like below; > > p:probe/reset_early_page_tables _text+12980741 > p:probe/copy_bootdata _text+12980830 real_mode_data=%di:u64 > p:probe/exit_amd_microcode _text+14692680 > p:probe/early_make_pgtable _text+12981274 address=%di:u64 > p:probe/x86_64_start_reservations _text+12981700 real_mode_data=%di:u64 > p:probe/x86_64_start_kernel _text+12981744 real_mode_data=%di:u64 > p:probe/reserve_ebda_region _text+12982117
Does this event cache support kernel modules too? AFAIK it can have a different address whenever loaded even on a same kernel. > > This event.cache file will be big (but much smaller than native > debuginfo :) ) if your kernel have many option embedded. > Anyway, you can compress it too. > > # wc -l event.cache > 33813 event.cache > # ls -sh event.cache > 2.3M event.cache > # ls -sh event.cache.gz > 464K event.cache.gz > > For setting up a probe event, you can grep the function name > and write it to tracing/kprobe_events, as below; > > # zcat event.cache.gz | \ > grep probe/vfs_symlink > /sys/kernel/debug/tracing/kprobe_events > > This can be applied for the remote machine only if the machine > runs on completely same kernel binary. Perhaps, we need some > helper tool to check it. While it's useful for "agent-less" systems, I think we also need to have a simple way to apply it with perf tools. Thanks, Namhyung > > Thank you, > > > --- > > Masami Hiramatsu (6): > [BUGFIX] perf-probe: Fix to handle optimized not-inlined but has no > instance > [DOC] perf-probe: Update perf-probe document > perf-probe: Add --output option to write commands in a standard file > perf-probe: Add --no-inlines option to avoid searching inline functions > perf-probe: Support $params special probe argument > perf-probe: Support glob wildcards for function name > > > tools/perf/Documentation/perf-probe.txt | 25 ++++++++++ > tools/perf/builtin-probe.c | 32 +++++++++++++ > tools/perf/util/dwarf-aux.c | 31 +++++++++++++ > tools/perf/util/dwarf-aux.h | 6 +++ > tools/perf/util/probe-event.c | 73 > +++++++++++++++++++++++-------- > tools/perf/util/probe-event.h | 4 +- > tools/perf/util/probe-finder.c | 74 > +++++++++++++++++++------------ > tools/perf/util/probe-finder.h | 6 ++- > tools/perf/util/util.h | 4 ++ > 9 files changed, 202 insertions(+), 53 deletions(-) > > -- > Masami HIRAMATSU > Software Platform Research Dpt. Linux Technology Center > Hitachi, Ltd., Yokohama Research Laboratory > E-mail: masami.hiramatsu...@hitachi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
